While working at Bell Labs, mathematician George Stibitz experimented with relays at home. He developed a circuit to add binary numbers, which led to a relay-based computer.
This Complex Number Calculator, operational in 1940, was demonstrated remotely at a conference using a Teletype – the first computer accessed over a phone line.
A typist entered problems suggested by attendees at the American Mathematical Society meeting at Dartmouth, New Hampshire in September 1940, and remotely operated the Complex Number Calculator in New York.View Artifact Detail
The Complex Number Calculator, made from 450 telephone relays, could multiply and divide 8-digit numbers. The last follow-on machine, the Model VI, was completed in 1950 and ended up at the Bihar Institute of Technology in India in the 1960s.View Artifact Detail